East Indian sandalwood oil has heretofore been available only from 60-80 year old East Indian sandalwood trees. This oil and various individual components of the oil are highly valued perfume bases and are used in large quantities by the perfume industry. The oil, however, is expensive and is in limited, and sometimes sporadic, supply. For this reason, a continuous effort has been made to synthesize the various components of sandalwood oil or similar synthetic materials which possess the several desirable nuances (e.g., woody, oily, green) of sandalwood oil.
The processes presented herein for preparing various sandalwood aroma components represent a portion of an extensive effort to obtain various components of sandalwood oil as well as substitutes therefor. Other processes and components related to the synthesis of sandalwood oil aroma-like components are described in the following publications:
I. U.S. Pat. No. 3,478,114 issued on Nov. 11, 1969, Title: PROCESS FOR MAKING ALPHA-SANTALOL
Covers the process: ##SPC3##
II. U.S. Pat. No. 3,662,007 issued on May 9, 1972, Title: PROCESS FOR PREPARING DIHYDRO-BETASANTALOL FROM 3-ENDO-METHYL-3-EXO (4'-METHYL-5'-HYDROXYPHENYL) NORCAMPHOR
Covers the process for preparing dihydrobeta-santalol from 3-endo-methyl-3-exo (4'-methyl-5'-hydroxypentyl) norcamphor comprising the steps of (1) reacting 1-endo methyl-3-exo(4'-methyl-5'-hydroxypentyl) norcamphor with either boric acid or boric anhydride to obtain the borate ester of 3-endo-methyl-3-exo(4'-methyl-5'-hydroxypentyl) norcamphor, and (2) reacting the borate ester reaction product of Step (1) with a phosphorous compound such as methyltriphenylphosphonium bromide and subsequently hydrolyzing the reaction product with water to obtain dihydro-beta-santalol.
iii. U.S. Pat. No. 3,662,008 issued on May 9, 1972, Title: PROCESS FOR PREPARING BETA-SANTALOL FROM 3-METHYLNORCAMPHOR
Covers the process for preparing beta-santalol from 3-methylnorcamphor comprising the steps of (1) alkylating 3-methylnorcamphor in strong base with an allyl halide; (2) reacting the reaction product of Step (1) with a methylmetallic compound, such as methyllithium, followed by hydrolysis; (3) brominating the reaction product of Step (2); (4) dehydrobrominating the reaction product of Step (3) with a base, such as sodium amide; (5) dehydrating the reaction product of Step (4) with a dehydrating agent, such as thionyl chloride; (6) reacting the reaction product of Step (5) with a compound, such as di(sec.iso-amyl)borane followed by an oxidation; (7) reacting the reaction product of Step (6) with (carbethoxyethylidene) triphenylphosphorane; and (8) reducing the reaction product of Step (7) with a reducing agent such as lithium aluminum hydride, to obtain beta-santalol.
iv. U.S. Pat No. 3,673,261 issued on June 27, 1972, Title: PERFUME COMPOUNDS AND PROCESS FOR PREPARING SAME
Covers the use in perfumery compounds having the following structures: ##SPC4##
v. U.S. Pat. No. 3,673,263 issued on June 27, 1972, Title: DIHYDRO-BETA-SANTALOL AND PROCESS FOR PREPARING DIHYDRO-BETA-SANTALOL FROM 3-ENDO-METHYL-3-EXO(4'-METHYL-5'-HYDROXYPENTYL) NORCAMPHOR
vi. U.S. Pat. No. 3,673,266 issued on June 27, 1972, Title: PROCESS FOR PREPARING DIHYDRO-BETA-SANTALOL FROM 3-ENDO-METHYL-3-EXO (4'-METHYL-5'-HYDROXYPENTYL) NORCAMPHOR
vii. Corey, et al., J. Am. Chem. Soc. 79, 5773 (1957), Title: THE SYNTHESIS OF ALPHA-SANTALENE AND OF TRANS-.DELTA.11,12-ISO-ALPHASANTALENE
Describes the following process sequence: ##SPC5##
However, none of the above processes explicitly or implicitly represent what are today deemed to be economically feasible techniques for providing the important and novel sandalwood aroma components having the generic structure: ##SPC6##
wherein Z is a moiety selected from the group consisting of: ##SPC7##
Furthermore, the structures of sandalwood aroma components set forth in the above-mentioned prior art are chemically different in kind from the novel compounds of this invention which have the generic structure: ##SPC8##
wherein X is a moiety selected from the group consisting of: ##SPC9##
and wherein R.sub.1 and R.sub.2 are each selected from the group consisting of hydrogen and methyl, at least one of R.sub.1 and R.sub.2 being hydrogen. The novel compounds of this invention have properties considered to be unobvious and advantageous over the compounds set forth in the aforecited prior art.